A novel 3-D tube-shaped buried poly-Si Pirani gauge for extended dynamic range with small footprint

We have developed a novel micromachined Pirani vacuum gauge employing a tube-shaped 3-D structure with enhanced rigidity and very low footprint because it is completely buried inside the silicon substrate. A CMOS-compatible three masks process was used to realize this new design, which allowed the fabrication, without stiction problems of a 3.2 mm long Pirani poly-Si tube with a 1.5 ¿m gap. Compared to previous gauges, the dynamic range is 100 times larger, ranging from 20 mPa to 10 kPa with a maximum sensitivity of 17.5 mV/decade.